For the welding of pipes, the cutting surfaces of the pipes have to be chamfered. However, the work of chamfering pipes cut at the bottom can be easily performed by engaging the pipes with a conventional chamfering apparatus, but the chamfering of the cutting surfaces of pipes that have been already installed, in the course of performing piping work, is very difficult
That is, during plant piping work, pipes with various diameters are placed in elevated places. Therefore, the chamfering of the pipes using a tool such as a portable grinder does not provide regular chamfered angles and is difficult because it is performed while rotating the grinder along the cutting surface of the pipes. Also, since the pipes are chamfered in elevated places, the work environment becomes poor.
In addition, when chamfering work is performed by installing a portable automatic chamfering apparatus on the cutting surfaces of pipes, chamfering apparatuses with various sizes should be provided for various diameters of pipes, and then a chamfering apparatus suitable for the diameter of pipes to be chamfered must be selected and used. Thus, the chamfering of the cutting surfaces of pipes during plant work using a pipe chamfering apparatus may be difficult.
In order to solve these problems, a portable pipe outer diameter-chamfering apparatus with an improved weldability has been suggested by Korean Patent No. 10-1497638 (issued on Feb. 24, 2015), in which circumscribing rollers are installed on the outside of a pipe to be a predetermined distance apart, an inscribing roller is installed on the inside of the pipe at a lower central part of the circumscribing rollers, the inscribing roller and the circumscribing rollers are closely adhered to the inside and the outside of the pipe, and then the pipe is chamfered with a cutting blade. The patented chamfering apparatus is moved manually, which is not problematic for pipes with a small diameter. However, in the case of pipes with a large diameter, it may not be easy to rotate the patented chamfering apparatus along the cutting surfaces of the pipes. Also, in the case of pipes having a large diameter and formed of a rigid material, it takes a long time to chamfer the pipes, and as a result, the worker's work efficiency decreases.